Do not always insist on conclusive proof

Sometimes doctors are willing to recommend a long-term preventive treatment in the absence of any conclusive proof of benefit, provided that we know the treatment is safe. This is especially true if the treatment also has a sound scientific basis and has been found beneficial by observational studies.

• Example: Observational studies have shown that people who take folic acid supplements have lower blood levels of homocysteine. Observational studies have also shown that higher blood levels of homocysteine increase the risk of coronary arteriosclerosis and heart attacks. Scientific studies have also shown that homocysteine can cause injury to the inner lining of arteries thus promoting atherosclerosis. Even though there is not yet conclusive proof from prospective placebo-controlled trials that taking folic acid actually prevents heart attacks, doctors are recommending that all adults take a daily multivitamin that contains folic acid because it is known to be safe over the long term. In this situation, doctors do not want to miss an opportunity to recommend something safe that possibly can prevent heart attacks while waiting for absolute proof of its effectiveness, which can be many years away.

Learn from history

Consider blood cholesterol as another example. Thirty years ago, observational studies suggested that high blood cholesterol (like homocysteine) could cause coronary artery disease and heart attacks. Even though there were no double-blind, placebo-controlled trials available, doctors in those days suspected (correctly) that lowering blood cholesterol could reduce heart attacks. They were recommending low fat diet and exercise to lower blood cholesterol, and medications such as statins only when diet and exercise failed. They also did one very important thing-they started numerous, large scale randomized, placebo-controlled trials to determine if lowering cholesterol actually prevents heart attacks.

Today the prospective trials they started have been completed. These trials have conclusively shown that lowering cholesterol (especially the bad LDL cholesterol) reduces heart attack risks and prolongs life. These trials further showed that the benefits of lowering cholesterol outweigh the risks of side effects of the statin medications. Therefore doctors today are much more aggressive than doctors of yesteryears. Doctors are much more willing to use medications such as statins to lower cholesterol, and the "normal cholesterol level" has been rapidly reduced.